The ``radical'' of a character is more or less its ``base component.'' For
example, $B;3(J is a character and a
radical, but appears as a component radical in characters such as:

Sometimes the radical appears different depending on how it's used. The
character $B?M(J is a radical, but can also appear like
$B%$(J. Some examples:

Actually, those last two are different versions of the same character, and
their radical really is
$B[)(J (which is, be careful now, different from
$BF|(J).
When the character was changed from $BPr(J $B"*(J $B2q(J
the $B[)(J component was lost from the character,
but it still remains as the traditional radical, but many dictionaries list
them both under $B?M(J. Is it ``correct''? I dunno' --
it's not like science with an absolute truth.

Sometimes the differences among forms is larger. The radical
$B?e(J
usually appears as the left part of $B=A(J (i.e. the part that's doesn't look
like a cross). Some examples:

More Illogicalness

Due to the historical (like, 2000 years) nature of kanji, there are lots of
illogical things about radicals. For example, the two radicals
$BSx(J $B8}(J
appear almost the same. Actually, there are two distinct radicals that do
appear exactly the same
(the $B7n(J part of

the first five have one radical, the second five have the other).

Some characters don't even physically contain the radical anymore, due to
changes over the years. The $BPr(J $B"*(J $B2q(J from above is one example.
Another is $BMh(J, whose traditional radical is
$B?M(J
because the old form of $BMh(J is $BPT(J.
Some other kanji/radical/orig sets are